Assessment of cracks using percolation dye tests in Rihand concrete dam, Uttar Pradesh, India

Performance of hydro power projects get affected predominantly due to chemical nature of water. If the hydro-environment happens to be aggressive it will affect the durability of concrete structure. Periodic health monitoring of these structures thus becomes mandatory. To carry out diagnostic gauging various destructive and non destructive tests are employed. The paper presents a case study of 934.21 m long, 91.44 m high Rihand Dam (24°12′9″N 83°0′29″E 24.2025°N 83.00806°E) situated in Pipri, Distt-Sonebhadra of U.P. (India) on river Rihand, a tributary of river Sone. It is a concrete gravity Dam, constructed during period 1954–1962. The Dam comprises of 61 independent blocks with ungrouted joints. The Power House is located at the toe of the Dam. It has installed capacity of 6 units of 50 MW each. The dam is experiencing both seepage and leaching phenomenon in its drainage gallery. It has developed cracks at various locations due to alkali silica reaction. These cracks are visible even on the surface of dam. Health monitoring of the dam thus necessitated the diagnostic gauging the path and depth of these cracks. Central Soil and Materials Research Station, New Delhi carried out detailed investigations on these cracks using percolation dye test in the dam concrete to assess their extent. The observations and their subsequent interpretation provided directional information for undertaking the remedial measures.